991489656 has 64 divisors (see below), whose sum is σ = 2534716800. Its totient is φ = 323077248.

The previous prime is 991489649. The next prime is 991489661. The reversal of 991489656 is 656984199.

It is a junction number, because it is equal to n+sod(n) for n = 991489596 and 991489605.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 389235 + ... + 391773.

It is an arithmetic number, because the mean of its divisors is an integer number (39604950).

Almost surely, 2^991489656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991489656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1267358400).

991489656 is an abundant number, since it is smaller than the sum of its proper divisors (1543227144).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991489656 is a wasteful number, since it uses less digits than its factorization.

991489656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2908 (or 2904 counting only the distinct ones).

The product of its digits is 4199040, while the sum is 57.

The square root of 991489656 is about 31487.9287346755. The cubic root of 991489656 is about 997.1551330736.

The spelling of 991489656 in words is "nine hundred ninety-one million, four hundred eighty-nine thousand, six hundred fifty-six".